The invention relates to an endless flexible torque-transmitting device as used in particular in a continuously variable transmission of a motor vehicle where the endless flexible torque-transmitting device is arranged in the torque flow between a first and a second pair of conical disks. The endless flexible torque-transmitting device has force-transfer elements that are perpendicular to the running direction and are engaged in openings of links that are parallel to the running direction, so that the force-transfer elements form articulated joints between the links.
The first pair of conical disks is connected, or at least connectable, to an input shaft of the transmission, and the second pair of conical disks is connected, or at least connectable, to an output shaft of the transmission. Transmissions of this kind can be used, e.g., in motor vehicles, and prove to have a particularly favorable effect on fuel consumption. Endless flexible torque-transmitting devices, also known as chains or chain belts, are known, e.g., from the German patent DE-PS 43 30 696, among others. In endless flexible torque-transmitting devices in accordance with the referenced patent, force-transfer elements that are oriented transverse to the running direction are combined in an articulated arrangement with links that are parallel to the running direction. To transmit a force or torque between the conical disk pairs of the transmission, end surfaces of the force-transfer elements or end surfaces of additional bolts are in force-transmitting contact-e.g. through friction forcesxe2x80x94with the pairs of conical disks, particularly with the lateral surfaces of the conical disks. The German patent DE-PS 43 30 696 discloses an endless flexible torque-transmitting device without additional bolts, in which the end surfaces of the force-transfer elements are in force-transmitting contact, specifically in frictional contact, with the pairs of conical disks. The European patent EP-PS 0 518 478 shows a variation of the same concept, where additional bolts are connected to the links for the transmission of a force or torque and the end surfaces of the bolts are in force-transmitting contact, specifically in frictional contact, with the pairs of conical disks.
In endless flexible torque-transmitting devices of this kind, at least a few of the force transfer elements or bolts are at any given time inside the space between the conical disks and enter into force-transmitting contact, specifically frictional contact, with the lateral surfaces of the pairs of conical disks, thereby transmitting a torque from one pair of conical disks through the endless flexible torque-transmitting device to another pair of conical disks. The transmission ratio can be varied by changing the radii of the path segments where the endless flexible torque-transmitting device is in contact with the pairs of conical disks. The torque is transmitted along the endless flexible torque-transmitting device through the force-transfer elements and the links.
As the endless flexible torque-transmitting device runs on its closed path around the conical-disk pairs of the transmission, the angle enclosed between the links of neighboring rows changes, so that the curvature radius of the endless flexible torque-transmitting device varies as the latter runs along its path through the transmission. Endless flexible torque-transmitting devices according to DE 43 30 696 have two force-transfer elements per articulated joint arranged in a pair where the two elements of each pair roll on each other. With this type of rolling connection, it is possible for the force-transfer elements to become jammed in the links, a condition that impedes the rolling motion of a force-transfer element on its counterpart.
The object of the present invention is to provide an endless flexible torque-transmitting device of the kind described at the beginning or a transmission comprising said flexible torque-transmitting device that is functionally more reliable and of the simplest construction possible.
In an endless flexible torque-transmitting device, particularly of the kind that runs in an endless loop around a first and second pair of conical disks in the torque-flow path of a continuously variable transmission of a motor vehicle and has pairs of force-transfer elements that are perpendicular to the running direction and pass through openings of links that are parallel to the running direction, so that the force-transfer elements establish articulated joints between the links, the object of the invention is met by an arrangement where at least individual pairs of force transfer elements are coupled to each other by at least one holder element per pair of force transfer elements.
It is particularly suitable for the purpose if the holder element is a ring-like holder element. It is particularly practical if the thickness of the holder element does not exceed the thickness of the links, so that the holder elements can be placed at unoccupied positions or gaps in the link pattern of the endless flexible torque-transmitting device.
It is practical if the ring-like holder element is a closed ring. It can also be practical if the ring-like holder element is a ring that is open at one place. In another embodiment, it is practical for the holder element to be an essentially U-shaped holder element.
Endless flexible torque-transmitting devices are configured advantageously as periodic arrays that repeat themselves every two links or every three links and will herein be referred to as two-link arrays or three-link arrays, respectively.
It is also advantageous if the arrangement of links in relation to a longitudinal median axis of the endless flexible torque-transmitting device is symmetric or else neither symmetric nor diagonal.
It is further practical if the links are of at least two different lengths. Together with the different lengths, it is practical if at least individual links have at least one extension on at least one end portion in relation to the running direction.
It is further advantageous according to another concept of the present invention if the links of the endless flexible torque-transmitting device have openings to accommodate the force-transfer elements and if the radially inner and/or radially outer portion (in relation to the loop of the endless flexible torque-transmitting device) of each opening has an essentially smooth or straight contour.
It is further advantageous according to another concept of the present invention if the links of the endless flexible torque-transmitting device have openings to accommodate the force-transfer elements and if the radially inner and/or radially outer border portion of each opening has at least one or two noses that extend in the inward or outward radial direction of the loop of the endless flexible torque-transmitting device.
The novel features that are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both in its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.